Abstract Purpose To evaluate the correlation between appendiceal size measured by contrast-enhanced CT of the abdomen and pelvis and the size of surgically removed appendixes on gross pathological examination. Materials and methods The initial database consisted of the cases of 301 children, collected over 2 years, of which 56 met inclusion criteria. Both the radiology and surgical pathology reports of these patients were reviewed. Results The mean size of appendixes meeting the CT size criteria of appendicitis was 10.3 mm, and that of the surgical pathology specimens was 10.4 mm. The pathological diagnosis of acute appendicitis was confirmed in 54 of 56 cases, yielding a positive predictive value of 96.4%. The Pearson product–moment correlation coefficient was calculated to be 0.5443 (95% CI 0.329 to 0.706). The slope of the linear correlation was 0.5788. The mean absolute difference in CT size versus pathological size was 2.2 mm. Conclusion The data reveal a strong correlation in ability of CT to predict the presence of acute appendicitis, with moderate correlation in the size estimate of acutely inflamed appendixes, as imaged on CT, and the pathological specimen status after appendectomy.